Pneumatic tire



Patentecl Sept. 29, 1936 mran STA-TBS PATEN'E FFEC -2,05a131 rmatmmrro arme poration ol Delaware Application April 18, 19341, Seria'i No. 721,115

2 Claims. (Cl. 152--14) This invention relates to improvements in pneumatic tires and. it relates more particularly to the provision of means for vercoming the tendency of such tires when in use on a vehicle 5 to pick up gravel and other small objects which are subsequently thrown from the tire by centrifugal force.

Since the advent of pneumatic tires having traction and non-skid tread surfaces formed with 10 spaced buttons, blocks, ribs and the like having grooves therebetween, such grooves, more particularly on the shoulder portions of the tire, have a tendency to pick up small objects such as gravel and to discharge such objects'with cnsiderable l force against the fenders and body of the vehicle. As a result small dents and other u nsightly marks appear on the vehicle and a disturbing n0ise is caused by the impingng of these objects against the fenclers. Also these objects are frequently 20 thrown into the path of other vehicles causing damage to headlights, windshields and other readily breakable parts.

Gravel throwing might be overcorne to a considerable extnt by using smooth tread tires, lont 25 the advantages of using traction and nonskid treads are so numerous that tire and vehicle manufactuiers are not willng to subject users to the hazardous risks encountered wth smooth tires merely to contro1 gravel throwing. Therefore it 30 is desirable to retain the advantages of thetrac tion and non-skid treads while controlling the gravel throwing tendencies of a tire and one of the objects of this invention is to provide a tire of this character with which gravel throwing is 5 substantially, if not completely, eliminated.

Another object is to provide a tire wherein the grooves of the tread design on the shoulder portionsof the tire at least, have protuberances projecting thereinto to reduce the size of the grooves 40 th;reby making it more difficult for the grooves to pick up small objects.

Other objects and advaritages of the invention will become apparent from the following description in conjunction with the accompanying draw- 45 ings wherein I have shown several embodiments of the invention. In this showi ne Fig. 1 is a plan view of a portion of a pneumatic tire showing the preferred arrangement of lar purpose.

Fig. 5 is a similar view taken substantially on line VV of Fig. 2,

Fig. 6 and Fig. 7 are partial plan views showing the arrangement of the protuberances on a different tread design, and 5 Fig. 8 is an enlarged partial perspective view illustrating the arrangement shown in Fig. 1.

In practicng the invention I have incorporated one form which it may assume in Figs. 1 and 3 wherein is provided a tire casing 5 having beads 10 6 and a rubber tread porton 'l. It will be understood that the casing 5 is formd with the customary rubberzed abric plies, chafing strips, a breaker strip and other conventional elements but these need not be illustrated in order te om derstanci the invention. In Figs. 1, 2, and 3 t will be noteci that I have illustrated the invention in connection with a well known tire tiead and. the form shown in Fig. 2 is a slightly modified embodiment of the invention shown in Figs. 1 and 3.

Referring to Figs. 1 and 3 the tread is ormecl with two circumerential ribs lll and ll, which are disposed at the circumferential shoulders of the tire. Centrally of the treacl, between the ribs ll and H a plurality of non-skid traction elements l2, arranged in staggered relation, are formed, whose outer surfaces are substantially of the same height in relief as the surfaces of the circumferental ribs. In this instance the e1ements 52 are substantially of damoncl and triangular shapes. Addtional rows of non-skid traction elements 93 and ll are arranged outwardly of the ribs li and lfl and the elements l3 witlo these ribs form the crcumferential shoulder portions of the tire, As shown, the elements i3 preferably are substantially triangular in shape while elements I l comprise a plurality of geometric orms blending nto substantially arrowheadlike figures, as clearly shown in Fig. 8. Transverse ribs |5 are arranged between elements l3 and the circumferential ribs and transverse ribs l6 are arranged between elements 14 and the circumferential ribs.

On their outer sides ribs l0 and II are provided with a, plurality of spaced semi-spherical protuberances I'l which project toward the elements I3 and |4 and reduce the size of the grooves I8 between these elements and the ribs. Similar protuberances I9 are arranged in spaced. relation on the short sides of the triangular elements I3 and project into grooves 20 for a simi- Aslightly different form of protuberance 2I is arranged on each side of each transverse rib I6 (see Fig. 4), this form of protuberance extending to the bottom the acljacent grooves trom points slightly below the outer surface of the ribs.

It will be observed that the iforegoing arrangement of protuberances substantially reduces the size of the grooves on the shoulder portions of the tire and retards the entrance of small objects into such grooves, while the traction and non-skid features of the tire are completely retained. Particular stress has been laid on the fact that the protuberances are preferably confined to the shoulder grooves and the reason Ior this is due to tests which have conclusively shown that the amountoi gravel thrown by the grooves arranged centrally of the tread is negligible. This is easily understood when it is realized that the centra! grooves undergo very little change in dimension as they move into and out of engagement with the surface over which a vehicle is traveling. On the other hand, the shoulder grooves materially change in width as they approach and leave such surface. As the shoulder grooves approach the road suriace they flrst increase in width and as the contact with the surface is made they decrease in width causing a pinching action of the tread elements which readily picks up small objects, such as gravel. Upon leaving the road surface these grooves again increase in width and as a result any small objects picked up wil! ordinarily be released and thrown from the tire. However, by providing the protuberances referred to herein I have substantially, ii not completely, prevented the shoulder grooves from picking up objects since the presence of these protuberances makes it diflicult for the objects to enter iar enough into the grooves to be pinched therein.

In confining my protuberances to the shoulder portions of the tire, I do not mean to convey the impression that I may not also use same in the grooves of the centra] tread design if such an arrangement is found to be deshable. My tests so far however, have indicated this to be unnecessary.

Refer'ing to Flgs. 2 and 5, I have shown a slightly modifled form and arrangement 0! the protuberances 22, wherein the number of protuberancesis reduced and each is elongated (see Fig. to extend. trom slightly below the surface of the tread elements to the bottom of the intervehing grooves. Also theprotuberances 22 are arranged in staggered relation in the grooves Il' and -20' on opposite sides of the wa1ls of these 'Ihe eflectiveness of the protuberances is not peculiar to the particular tread design shown in Flgs. 1 and 2, but may beused with many other designs, one of which I have shown ior example in Flgs. 6 and 7. In this showing the tread comprises aplurality of spaced circumferential ribs 23, 24, 25, and 26, with the outer ribs 23 and 25 disposed at the shoulders of the tire. Sharp lateral projections 21 are formed at spaced points on all these rlbs, and on ribs 23 and 26 indentations 23 are iformed opposite the projections. The traction non-skid elements 29 and 30 are completely isolated trom the circumierential ribs thereby torming grooves 3I and 32 which will pick up objects if no protuberances are provided to prevent such action. However, by providing spaced protuberances 33 on the inner side of ribs 23 -and 23 and on the short sides of triangular elements 29, similar to protuberances l| and I!) in Flg. 1, the grooves 3! and 32 are efiectively re duced in size to retard entrance of small objects, while the desirable features of the traction and. non-skid design are retained.

Flg. 'l shows the protuberances 34, which preferably are similar to protuberances 22 in Fig. 2, arranged in staggered relation in the grooves 3! and 32'.

It is believed to be obvious that my invention provides a practical solution tor eliminating the throwing of small objects by a tire when in use, while retaining all the desirable features of the tmotion and non-skid tread.

Although I have illustrated several forms of the invention, it will be apparent to those skilled in the art that the invention is not limited to such forms but that various modifications may be made without departing trom the spirit of the invention pr trom the scope of the suh-joinedclams.

- What1claim is:

1. A pneumatic tire having projections thereon with grooves therebetween and pebble ejectng protuberances on the sidewalls of said grooves extending laterally of said grooves, the lower and upper sides of said protuberances being spaced respectively trom the bottoms of said grooves and the upper edges thereof.

2. A pneumatic tire having a groeve in the periphery thereof, and a pebble-ejecting portion running along and protruding laterally from a side wall of the groeve, and having the upper and lower sides thereoi spaced respectively from the top and bottom portions of the groeve.

HAROLD A. BRITTAIN. 

